The GKTECH Z33 350z/G35 rear subframe collars are used to eliminate axle tramp and to also tighten up the rear end giving more precise control of the vehicle under harsh driving conditions. The OEM bushes are designed more for comfort than performance and by filling the voids within the factory subframe bushes it makes the subframe much more "as one" with the car. Noise isn't drastically effected compared to going to solid subframe bushes and these inserts are far easier to install than going to a solid subframe bush. - 8 Piece Set - Semi-solid are manufactured from proprietary 90sHA material - Solid are CNC machined from a 6061-T6 aluminium Vehicle Compatibility: - Nissan Z33 350z - Infiniti G35 Coupe (2003-2007) - Infiniti G35 Sedan (2003-2006)